Apparatus for regulating pulp level in ball mills



oct. 2,1, 1941.

R. c. NEwHoUsE APPARATUS FOR REGULATING PULP LEVEL IN BALL MILLS Filed Oct. 25, 1939 Patented Oct. 2l, 19.41

APPARATUS Foa 1N REGULATIN G PULP LEVEL BALL MILLS Ray C. Newhouse, Wauwatosa, Wis., -assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application October 25, 1939, Serial No. 301,10il

3 Claims.

This invention relates to a grinding mill and to a method of grinding ore, rock and othe materials.

It is an object of this invention to provide a wet grinding mill in which the ground material is removed from the grinding chamber adjacent the cylindrical Walls of the drum.

It is another object of this invention to pro vide positive pocket lifting means to raise such material from the bottom of the discharge chamber to a conical discharge head.

A further object of this invention is to provide 'a novel discharge means for a wet grinding mill which makes it possible to regulate the level of material in the mill while it is rotating in use.

Other objects will become apparent from the following description taken in conjunction with the attached drawing in which:

Fig. l is a central vertical section view through a wet grinding mill embodying features ci this invention;

Fig. 2 is a developed view through a section of the discharge head taken on the line II-II of Eg. l:

Fig. 3 is a similar view on theline III-III of Fig. l; and

Fig. 4 is a perspective view of two segmental lifting pockets which form part of the discharge head of this invention.

Ecient grinding of material requires careful control of many factors. AIn addition to the rate and quality of feed and the weight and size of `grinding media and speed of rotation of the mill,

the amount of circulating load, the means for,

removing ground material from the grinding chamber and the level of material in the chamber are factors of extreme importance. A greater degree of control than has hitherto been possible over these last three factors is obtainable with the apparatus and method of this invention.

Referring to the drawing, Fig. 1 illustrates a rotary ball mill it, provided with an inlet trunnion il and a discharge trunnion I2, and containing a charge ci balls l and pulp (or slurry) ld. The pulp is discharged from the mill by means of the usual cone i8, provided with radial ribs Il'.

The pulp or ground material is permitted to ow out of the grinding chamber only through a restricted area adjacent the periphery oi' the drum. The discharge end wall of the drum conssts of a central blank or plate i8 and an annulus between said plate and cylindrical wall of the drum. n the mill illustrated herein, this which are provided with grid portions 2li near the periphery of the annulus. The pulp ows out of the grinding chamber through these peripheral grids.

The discharge head of the present invention comprises a plurality of positive lifting pockets 25. In the exemplication illustrated herein, each of these pockets 25 is formed by segmental plates 22. inclined segment plates 23 formed at an acute angle with plates 22and arcuate anges 2d. Radially inward of inclined segment plates 23 are plate sections 2t which are parallel to plates 22 and are connected to inclined segment plates 23 by means of webs 2l. Radial rib 2B connects one edge ci plate 2t with an edge of segmental plate 22, and these ribs 28 form continuations of ribs l?. It will be understood that as the mill rotates, pockets formed by the mem# bers 22, 23, 2d, 2d, 2l will positively lift any pulp which has left the grinding chamber through grids 2E, and will deposit such pulp on discharge cone it by means of ribs 28 and il.

Mounted in stationary housing or bracket 3d is a trunnion valve Si carried by threaded rod 32, which may be threaded in bracket 30. Manual adjustment of valve 3l relative to a valve seat in trunnion l2 maybe eiected by threading rod- 32 toward and away from trunnion l2. This regulation of valve 3l is possible whether the mill is stationary or rotating in use. suitable valve may be substituted'ior the v-alve described above.

With the construction described above, pulp is withdrawn adjacent the periphery of the mill and positively lifted to thedischarge cone. Any pulpwhich is prevented from flowing out through the trunnion l2, because of the restriction of valve 3i, will ow back into the pockets 25 and thereby regulate the amount of pulp iiowing through the grid portions 2li. The rate of discharge is susceptible of regulation at all. times by means of valve 3l. In this way the circulating load and the level of the pulp in the mill can be very easily regulated to suit varying speed conditions.

As used in the speciiication and claims,'the term pulp also includes slurry, as well as other materials being ground.

It will be clear to thoseskilled in the art that various modifications and variations may be made in the embodiment disclosed herein. Such modicatlons and variations are included within the invention as defined in the appended claims.

It is claimed and desired to secure by Letters annulus cots of segmental grid plates I 9 55 Patent:

Any other 1. Discharge means for a rotary grinding mill comprising an end wail provided with a discharge trunnion, a material retaining imperiorate wall spaced from said end wall and provided with apertures adjacent only the peripheral wall o! said drum, and radial ribs extending across the entire space between said end wall and said material retaining wall, at least those portions of'1 between said plates and said arcuate wall, said second segmental plate being provided with a portion adjacent the smaller. end thereof substantially parallel to said first segemental plate, and a web connecting said angular and parallel portions.

3. Discharge' means for a rotary grinding mill comprising an end wall provided with a discharge t trunnin, a material retaining imperforate wall spaced from said end wall and provided with apertures adjacent only the peripheral wall of said drum, and radial ribs extending across the entire space between said end wail and said material retaining wall,at least those portions oi said ribs which are coextensive with the apertured peripheral portion of said material retaining wall being arranged at an acute angle with said end wall, each of said ribs substantially abutting its circumferentialiy adjacent ribs.

RAY C. NEWHOUSE. 

